Explosive tape



D. M. WELSH May 23, 1967 EXPLOS IVL. TAP 1 Filed Oct. 18, 1965' FIG.4

INVENTOR David Martin WELSH AGENT United States Patent 939,8 6 Claims. (Cl. 102-27 ABSTRACT OF THE DISCLOSURE A flexible weftless explosive tape comprises parallel co-planar longitudinal detonating cords bonded together by means of an adhesive. The tape can be provided with an adhesive backing.

This invention relates to an improved explosive tape and, more particularly, to an explosive tape which is possessed of such flexibility that it can be folded back on itself or tied in knots at any area without forming a crack at the bends.

Explosive compositions have heretofore been described (cg. in United States Patents Nos. 2,992,087 and 2,999,- 743) which can be formed into flexible, non-resilient sheets. Despite their many useful properties, however, the said sheets have been found to lack the necessary flexibility to permit their being folded back on themselves without tearing or cracking and hence no satisfactory explosive tape can be made therefrom.

A partial solution to the aforesaid flexibility problem has been proposed in United States Patent No. 3,169,478 which describes an explosive tape adapted to be folded at designated areas because of the presence in the tape of a plurality of slits, essentially equal in length, arranged in echelon across the tape, torsion bars being defined by the section of the tape lying between the slits. As explicity pointed out by the patentee, the tape can only be folded at designated areas and hence is not completely flexible, being thus unsuitable for many applications such as, for example, the strapping and/or lining of military or other containers which must be quickly opened.

It is the primary object of this invention to provide an explosive tape which is completely flexible in the sense that it can be folded at any area without any resultant tearing, discontinuities and hiatus of the explosive composition in the region of the fold. Additional objects of the invention Will appear hereinafter.

The improved explosive tape of this invention is weftless and comprises essentially a plurality of strands bonded together in parallel longitudinal relationship by means of an adhesive, at least one of said strands being a textile covered detonating cord.

Textile covered detonating cord or fuse is a well-known article of commerce. It is an elongated cord-like material consisting of a core of high explosive such as pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), nitromannite, lead azide, lead styphnate, tetryl, trinitrarnine, TNT or cyclotetramethylene tetranitramine (HMX), confined within a textile sheath. This sheath is normally surrounded by a thermoplastic covering for waterproofing purposes when used in the field. A typical textile covered detonating fuse has a uniform velocity of detonation of the order of 6000 meters per second and comprises a core of 30-50 grains per foot of PETN having a specific surface of 500 square centimeters per gram, a textile sheath surrounding said core to contain the same, and, preferably, a waterproofing layer of thermoplastic surrounding said textile sheath. A more recently developed textile covered detonating cord, referred to in the trade as low energy cord, is described in United States Patent No. 3,125,024 and comprises a core of high explosive such as PETN having a specific surface of at least about 900 square centimeters per gram (e.g. 900-3400 sq. cm./ gr.) in a concentration of at least 1.5 grains per foot of length for specific surfaces of up to 3400 square centimeters per gram (e.g. 1.5-10 grains per foot), confined within a textile sheath preferably surrounded by a thermoplastic layer.

By specific surface is meant the surface area per unit weight of the high explosive in powder form. It is measured by the standard nitrogen adsorption test using the BET equation and apparatus. (See Encyclopedia of Chemistry, Reinhold, 1957, or Small Particle Statistics by G. Herdan, Buttleworth, 1960.)

The high explosive content of the detonating cord strand or strands of the explosive tape of the invention can be as low as the detonation-cross propagation reliability will permit for any given high explosive ingredient and can be as high as demanded by the application or use of the tape.

As previously mentioned, the tape may contain as little as one textile covered detonating cord strand bonded in parallel longitudinal relationship to at least one ordinary textile strand. If more than one textile covered detonating cord strands are present in the tape, they can be located in juxtaposition or in alternate relationship with ordinary textile strands. The tape can of course wholly consist of strands of detonating cord. The textile covered detonating cord strands may, if desired, have a thermoplastic covering for waterproofing purposes.

The explosive tape may be provided with an adhesive backing and thus take the form of a standard adhesive tape or the weftless adhesive glass fibre tapes. It can be completely or partially enclosed in metal foil or covered with thermoplastic. Where RDX is the high explosive ingredient of the detonating cord, for example, the tape can be covered with a polyamide or a polyester such as polyethylene terephthalate. The tape can also be so designed that although it will cross propagate detonation within itself, it will not cross propagate detonation when overlapping with another piece of the same tape.

Any flexible adhesive can be used for bonding the strands of the tape together in parallel longitudinal relationship as long as such adhesive has no detrimental effect on the detonating cord. Water-based latex adhesives are particularly suitable.

The invention will be more fully illustrated by reference to the accompanying drawing wherein:

FIGURE 1 is a top view of an explosive tape consisting wholly of bonded strands of detonating cord;

FIGURE 2 is an end view of the same tape;

FIGURE 3 is a top view of an explosive tape comprising alternate strands of detonating cord; and

FIGURE 4 is an end view of the tape of FIGURE 3.

All figures are slightly enlarged in dimension for clarity.

In FIGURES 1 and 2 1 designates the tape consisting of eight strands of detonating cord 2 bonded together in parallel longitudinal relationship by adhesive 3. 4 represents the core of high explosive of each strand of detonating cord 2 while 5 represents the textile sheath confining core 4.

In FIGURES 3 and 4, the tape 6 is shown as being made of four strands of detonating cord 7 bonded to four ordinary textile strands 8 in alternate parallel longitudinal relationship by means of adhesive 9. The high explosive core 10 of each strand 7 is surrounded by a textile sheath 11.

The following example serves to illustrate further one specific embodiment of the explosive tape of the invention.

0 Example A tape approximately wide, of the kind shown in FIGS. 1 and 2 of the drawing, was fabricated by bonding together with a water based latex adhesive eight strands of textile covered detonating cord having a diameter of approximately 0.06", the explosive Core of which contained 4 grains per foot of PETN and was enclosed in a textile braid. The tape was completely flexible and was detonated by applying a conventional No. 6 blasting cap to one end thereof.

Because of its flexibility, the improved explosive tape of this invention can be formed into a linear shaped charge and applied to those uses which linear shaped charges are normally applied to.

The tape can, of course, be used where prior art sheet "explosives have heretofore been used, e.g. for joining metallic objects, metal hardening, etc. It is particularly suitable for strapping and/ or lining military containers or the like for quick opening thereof.

What I claim is:

1. A weftless explosive tape comprising essentially more than two flexible strands of substantially the same cross section bonded together "by means of an adhesive in parallel, co-planar longitudinal relationship when in the flat condition, at least one of said strands being an elongated cord-like material having a core of high explosive confined within a textile sheath, said tape being further characterized by complete flexibility across its width and length.

2. An explosive tape as claimed in claim 1 comprising at least two strands of said elongated cord-like material, the high explosive of the core of said elongated cord-like material being present in such a concentration as to en- 5 sure cross-propagation of the explosive detonation.

'3. -An explosive tape as claimed in clailn 2 wherein the high explosive of the core of the elongated cord-like material is pentaerythritol tetranitrate.

4. An explosive tape as claimed in claim 1 wherein 10 each of the strands is an elongated cord-like material as defined in said claim.

5. An explosive tape as claimed in claim 1 wherein ordinary textile strands alternate with strands of an elongated cord-like material as defined in said claim.

15 6. An explosive tape as claimed in claim 1 provided with an adhesive backing.

References Cited by the Examiner FOREIGN PATENTS 797,472 7/1958 Great Britain.

BENJAMIN A. BORCI-IELT, Primary Examiner.

O V. R. PENDEGRASS, Assistant Examiner. 

1. A WEFTLESS EXPLOSIVE TAPE COMPRISING ESSENTIALLY MORE THAN TWO FLEXIBLE STRANDS OF SUBSTANTIALLY THE SAME CROSS SECTION BONDED TOGETHER BY MEANS OF AN ADHESIVE IN PARALLEL, CO-PLANAR ONGITUDINAL RELATIONSHIP WHEN IN THE FLAT CONDITION, AT LEAST ONE OF SAID STRANDS BEING AN ELONGATED CORD-LIKE MATERIAL HAVING A CORE OF HIGH EXPLOSIVE CONFINED WITHIN A TEXTILE SHEATH, SAID TAPE BEING FURTHER CHARACTERIZED BY COMPLETE FLEXIBILITY ACROSS ITS WIDTH AND LENGTH. 